Method and apparatus for compressor control and operation via detection of stall precursors using frequency demodulation of acoustic signatures
First Claim
1. A method for monitoring and controlling a compressor, comprising:
- (a) monitoring at least one compressor parameter;
(b) analyzing the monitored parameter to obtain time-series data;
(c) filtering the time-series analyzed data using a band-pass filter centered on a particular frequency of interest;
(d) frequency demodulating the filtered time-series data to produce an output signal, and processing the output signal to determine stall precursors, the frequency demodulation using a reference frequency that is the same as the center frequency of interest;
(e) comparing the stall precursors with predetermined baseline values to identify compressor degradation;
(f) performing corrective actions to mitigate compressor degradation to maintain a preselected level of compressor operability; and
(g) iterating said corrective action performing step until the pre-selected level of compressor operability is met, whereby the monitored compressor parameter lies within predetermined threshold.
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Abstract
An apparatus for monitoring the health of a compressor comprising at least one sensor operatively coupled to the compressor for monitoring at least one compressor parameter, a calibration system coupled to the at least one sensor, the calibration system performing time-series analysis on the monitored parameter, a processor system for processing and computing stall precursors from the time-series analyzed data, a comparator that compares the stall precursors with predetermined baseline data, and a controller operatively coupled to the comparator which initiates corrective actions to prevent a compressor surge and stall if the stall precursors deviate from the baseline data which represents predetermined level of compressor operability. The processor system preferably includes a frequency demodulator and a system for processing the frequency demodulated signals to extract stall precursor characteristics.
48 Citations
35 Claims
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1. A method for monitoring and controlling a compressor, comprising:
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(a) monitoring at least one compressor parameter;
(b) analyzing the monitored parameter to obtain time-series data;
(c) filtering the time-series analyzed data using a band-pass filter centered on a particular frequency of interest;
(d) frequency demodulating the filtered time-series data to produce an output signal, and processing the output signal to determine stall precursors, the frequency demodulation using a reference frequency that is the same as the center frequency of interest;
(e) comparing the stall precursors with predetermined baseline values to identify compressor degradation;
(f) performing corrective actions to mitigate compressor degradation to maintain a preselected level of compressor operability; and
(g) iterating said corrective action performing step until the pre-selected level of compressor operability is met, whereby the monitored compressor parameter lies within predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
i. filtering the time-series analyzed data to reject undesirable signals and produce a filtered output signal;
ii. frequency demodulating the filtered signal to produce an output signal with an amplitude corresponding to the instantaneous frequency of a locally dominant component of the input signal;
iii. low-pass filtering the frequency demodulated signal to reduce noise interference; and
iv. processing the low-pass filtered signal to identify a stall precursor.
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3. The method of claim 2, wherein the step of frequency demodulating the filtered signal is performed by a frequency demodulator, and wherein the center frequency is set to a tip passage frequency of the compressor'"'"'s blades.
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4. The method of claim 3 wherein the tip passage frequency is defined by the product of a number of the compressor'"'"'s blades and the rotational rate of the compressor'"'"'s rotor.
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5. The method of claim 1 wherein said corrective actions are initiated by varying operating line parameters.
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6. The method of claim 5 wherein said corrective actions include reducing the loading on the compressor.
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7. The method of claim 5 wherein said operating line parameters are set to a near threshold value.
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8. The method of claim 1 wherein the at least one compressor parameter is the dynamic pressure of gases flowing through the compressor.
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9. The method of claim 1, wherein the at least one compressor parameter is selected from the group comprising pressure, velocity, force and vibration.
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10. A method for monitoring and controlling a compressor, comprising the steps of:
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(a) monitoring at least one compressor parameters (b) analyzing the monitored parameter to obtain time-series data;
(c) processing the time-series data using a frequency demodulator to produce an output signal, and processing the output signal to determine stall precursors;
said processing steps comprising;
i. filtering the time-series analyzed data to reject undesirable signals and produce a filtered output signal;
ii. frequency demodulating the filtered signal to produce an output signal with an amplitude corresponding to the instantaneous frequency of a locally dominant component of the input signal;
iii. low-pass filtering the frequency demodulated signal to reduce noise interference; and
iv. processing the low-pass filtered signal to identify a stall precursor;
(d) comparing the stall precursors with predetermined baseline values to identify compressor degradation;
(e) performing corrective actions to mitigate compressor degradation to maintain a preselected level of compressor operability; and
(f) iterating said corrective action performing step until the monitored compressor parameter lies within predetermined threshold; and
wherein filtering of the time-series data is performed by a band-pass filter, the center frequency (fc) of the band-pass filter is centered on a tip passage frequency of compressor blades, said tip passage frequency is defined by the product of a number of compressor blades and the rotational rate of a rotor.
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11. An apparatus for monitoring the health of a compressor, comprising:
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at least one sensor operatively coupled to the compressor for monitoring at least one compressor parameter;
a calibration system coupled to said at least one sensor, said calibration system performing time-series analysis (t,x) on the monitored parameter;
a processor system for processing and computing stall precursors from data based on the time-series analyzed parameter, the processor system further comprising;
a band pass filter for producing filtered signals, the band-pass filter centered on a particular frequency of interest;
a first system including a frequency demodulator for demodulating said filtered signals to produce frequency demodulated signals;
the frequency demodulator using a reference frequency that is the selected center frequency of interest; and
a second system for processing said frequency demodulated signals to extract signal characteristics;
a comparator that compares the stall precursors with predetermined baseline data; and
a controller operatively coupled to the comparator, said controller initiating corrective actions to prevent a compressor surge and stall if the stall precursors deviate from the baseline data, said baseline data representing predetermined level of compressor operability. - View Dependent Claims (12, 13, 14, 15, 16, 17)
a look-up-table (LUT) with memory for storing compressor data including stall precursor data.
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13. The apparatus of claim 12 wherein the corrective actions are initiated by varying operating limit line parameters.
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14. The apparatus of claim 13 wherein said operating limit line parameters are set to a near threshold value.
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15. The apparatus of claim 11, wherein the center frequency is set to a tip passage frequency of the compressor'"'"'s blades.
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16. The apparatus of claim 15, wherein the tip passage frequency is defined by the product of a number of the compressor'"'"'s blades and the rotational rate of the compressor'"'"'s rotor.
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17. The apparatus of claim 11 wherein the at least one compressor parameter is the dynamic pressure of gases flowing through the compressor.
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18. In a gas turbine of the type having a compressor, a method for monitoring the operability of the compressor comprising:
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(a) monitoring at least one compressor parameter;
(b) analyzing the monitored parameter to obtain time-series data;
(c) processing the time-series data using a band-pass filter centered on a particular frequency of interest to filter the time-series data and a frequency demodulator using a reference frequency that is the same as the center frequency to produce an output signal by demodulating the filtered time-series data, and processing the output signal to determine stall precursors;
(d) comparing the stall precursors with predetermined baseline values to identify compressor degradation;
(e) performing corrective actions to mitigate compressor degradation to maintain a preselected level of compressor operability; and
(f) iterating said corrective action performing step until the monitored compressor parameter lies within predetermined threshold. - View Dependent Claims (19, 20, 21, 22)
i. filtering the time-series analyzed data to reject undesirable signals and produce a filtered output signal;
ii. frequency demodulating the filtered signal to produce an output signal with an amplitude corresponding to the instantaneous frequency of a locally dominant component of the input signal;
iii. low-pass filtering the frequency demodulated signal to reduce noise interference; and
iv. processing the low-pass filtered signal to identify a stall precursor.
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20. The method of claim 18, wherein the center frequency is set to a tip passage frequency of the compressor'"'"'s blades.
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21. The method of claim 18, wherein the band-pass filter has a pre-specified frequency width of 8 Hz.
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22. The method of claim 18 wherein the at least one compressor parameter is selected from the group comprising pressure, velocity, force and vibration.
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23. An apparatus for monitoring and controlling the health of a compressor, comprising:
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means disposed about the compressor for monitoring at least one compressor parameter;
means for computing stall measures, said computing means including means for producing signals filtered to reject frequencies outside a band of frequencies of a pre-specified width, means for frequency demodulating said filtered signals, and means for processing said frequency demodulated signals to extract signal characteristics for computing the stall measures;
means for comparing the stall measures with predetermined baseline values; and
means for initiating corrective actions if the stall measures deviate from said baseline values. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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31. A method for monitoring and controlling the health of a compressor, comprising:
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providing a means disposed about the compressor for monitoring at least one compressor parameter;
providing a means having a frequency demodulating algorithm for computing stall measures, said computing means including means for producing signals filtered to reject frequencies outside a band of frequencies of a pre-specified width, means for frequency demodulating said filtered signals, and means for processing said frequency demodulated signals to extract signal characteristics for computing the stall measures;
providing a means for comparing the stall measures with predetermined baseline values; and
providing a means for initiating corrective actions if the stall measures deviate from said baseline values. - View Dependent Claims (32, 33, 34, 35)
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Specification